When I was a kid growing up in Lynn, Mass it would be a common sight seeing people remove their shoes before a fight. Kicking someone barefoot was considered simple assault and battery. Kicking someone with shoes on was assault with a deadly weapon.

Removing your shoes told your opponent (and the gathering crowd) : "Yeah, I'm planning on kicking you and yeah, I know I'll likely get arrested for it later." Sort of an example or bluff that this isn't your first dance.